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        <td class="header">&nbsp; ETAD Correction for Sentinel-1 Products<br>
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<h3>ETAD Correction for Sentinel-1 Products</h3>
<p> The operator applies the ETAD correction to Sentinel-1&nbsp;TOPS
SLC, Stripmap and GRD products.
The Extended Timing Annotation Dataset (ETAD) for Copernicus Sentinel-1
is a new auxiliary product developed by ESA (with DLR as contractor),
providing users with corrections to improve the geometric accuracy of
Sentinel-1 Products. For Sentinel-1 TOPS SLC images, the&nbsp;geometric
accuracy can be improved to centimetric levels. The product contains
analysis-ready layers for removing the atmospheric path delays, the
solid Earth tidal deformation, and the Sentinel-1 system specific
effects related to the IPF SAR processor.&nbsp;The&nbsp;operator computes
for all pixels the range and azimuth offsets based on the user selected
ETAD correction layers, then resamples the image based on the computed range and
azimuth offsets.&nbsp;</p><p>For
TOPS SLC product,&nbsp;the&nbsp;operator currently requires the users
split the product into sub-swathes and applies the ETAD correction to
the split product. It also requires the users to provide the ETAD
product correspondingto the Sentinel-1 product. In future, the ETAD product will be downloaded automatically. </p><h4>Input</h4>
<ul>
    <li>The input to this operator could be the split Sentinel-1 TOPS SLC product, Stripmap SLC product or GRD product.</li>
</ul>

<h4>Output</h4>
<ul>
    <li>The output of the operator is the ETAD corrected product.</li>
</ul>


<h4>Parameters Used</h4>
<ul>
    <li>Resampling Type: The interpolation methods used for resampling the image. </li><li>ETAD File: The ETAD product&nbsp;provided in a SAFE product container.</li><li>ETAD
Correction Layers: The range and azimuth correction layers available
for ETAD correction. Note that the "Sum Of Range Corrections" layer
contains all the individual range correction layers in it, and the "Sum
Of Azimuth Corrections" contains all the individual azimuth correction
layers. Therefore, they should not be selected together with any of the
individual layers.</li></ul>
<p><img style="width: 447px; height: 445px;" alt="" src="images/S1ETADCorrectionOp.jpg"><br></p><br>
<h3>Reference:</h3>
<p>[1] S1-ETAD Project: Product definition Document, Doc. ID ETAD-DLR-PS-0002, Issue 2.4, Date 06.03.2023, Page 1 of 37.</p><p>[2] S1-ETAD: Product Format Specification Document, Doc. ID ETAD-DLR-PS-0014, Issue 1.8, Date 06.03.2023, Page 1 of 63.</p>

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